Today in 490 BC the Battle of Marathon occurred, where a small Athenian force defeated the Persian Empire.
In 1217, French prince Louis & English King Henry III sign a peace treaty.
There are only 110 days remaining until the end of the year.
There's a possibility that the new IPhones will be announced today.
https://www.cnet.com/news/when-is-the-2018-iphone-apple-event-september-12/If you're in Chicago today:
Free Baroque concert -
https://www.baroque.org/Seasons/2018-2019/baroque-in-the-parkOr, you could catch a free movie -
https://www.chicagoparkdistrict.com/movies-parks(Space Jam , and Justice League are playing)
The world music festival is also happening -
https://www.cityofchicago.org/city/en/depts/dca/supp_info/world_music_festival.html/ If you're in Germany, you could always investigate he 9th Conference on the Mechanical Behavior of Salt (SaltMech IX) - it will take place from September 12 – 14, 2018 at the BGR in Hannover, Germany.
https://www.saltmech.com/And for budding - or experienced - programmers, the .NET conference (streaming and local) starts today.
https://www.dotnetconf.net/ 
Edit: Almost forgot, if you dig air races, the National Championship Air Races are happening in Reno, today through Sunday.
http://garyleeprice.com/reno-air-races-2018/